Fermentation is a conversion of carbohydrates to organic acids or other compounds using bacteria strains.
Fermented milk products are major consumer products. Fermented milk products can be, for example, cheeses, buttermilks and yoghurts. Fermented milk products are manufactured by fermenting a milk source.
A milk source, for example milk, contains the carbohydrate lactose. During fermentation of the milk source the bacteria strains ferment the carbohydrate lactose to produce lactic acid. The production of lactic acid results in an acidification of the milk source during the manufacture of the fermented milk product. During fermentation of the milk source, other reactions may occur between other substances present in the milk source and the bacterial strains.
A fermentation of the milk source with bacteria strains is responsible for a generation of a flavour and aroma in the fermented milk products. Furthermore the fermentation of the milk source with the bacteria strains increases a shelf-life of the fermented milk products.
The bacteria strains used to ferment the milk source can be lactic acid bacteria strains. The lactic acid bacteria strains include Lactobacillus, Leuconostoc, Pediococcus, Lactococcus and Streptococcus; as well as the more peripheral Aerococcus, Carnobacterium, Enterococcus, Oenococcus, Sporolactobacillus, Teragenococcus, Vagococcus and Weisella; these lactic acid bacteria strains belong to the order Lactobacillales.
An international patent application publication No. WO 2008/049581 by the Applicant Nestec SA is titled “Taste and flavour modulation by biotransformation in milk products”. The international patent application publication No. WO 2008/049581 discloses a method to promote a non-savoury flavour in a food product.
An international patent application publication No. WO 02/085131 by the Applicant New Zealand Dairy Board is titled “Method of preparing savoury-flavoured products by fermentation of proteins”. The international patent application publication No. WO 02/085131 discloses a method for the manufacture of a savoury flavoured product from a source of protein using a combination of two distinct strains of bacteria. The source of protein may be a plant soy, wheat, rice, milk or whey. A first strain of bacteria is selected from the group Macrococcus, Micrococcus, Entercoccus, Staphylococcus, Brevibacterium, Anthrobacter and Corynebacterium, preferably Macrococcus caseolyticus. A second strain of bacteria is selected from the lactic acid bacteria—Lactococcus, Lactobacillus, Pediococcus or Leuconostoc. The savoury flavoured product may be combined with other ingredients to form products such as cheese, protein-water gels, yoghurts, creams, custards, sauces and confectionary products.
An international patent application publication No. WO 02/00845 by the Applicant Nizo Food Research is titled “Enhanced flavour production in or relating to food by cultivation of various food grade micro-organisms”. The international patent application publication No. WO 02/00845 discloses new mixed cultures of two or more micro-organism strains wherein at least one of the micro-organism strains which are comprised in said mixed culture is individually selected on the basis of its ability to perform part of an enzymatic pathway, and said two or more selected micro-organism strains together form a complete pathway towards a desired flavour component. The mixed culture is a culture for the production of a fermented product, such as yogurt or cheese or sausage. Said two or more micro-organism strains are preferably co-cultivated. Particular and preferred embodiments are starter cultures for the manufacture of cheese. The mixed culture comprising a combination of various Lactoccocus strains and a combination of a Brevibacterium strain and a Staphylococcus strain, respectively.
An article by Monnet et al. in a Journal of Microbiological Methods 37 (1999) pp 183-185 is titled “An improved method for screening alpha-acetolactate producing mutants”. The article by Monnet et al. discloses that a bacterial strain Lactococcus Lactis ssp. Lactis Biovar. Diacetylactis is used in the dairy industry to produce diacetyl. Diactetyl is a major flavour compound in cultured dairy products.
An article by Boumerdassi et al. in a Journal of Dairy Science Vol. 80 Issue 4 (1997) pp 634-639 is titled “Effect of citrate on production of diacetyl and acetoin by Lactococcus Lactis ssp. Lactis CNRZ 483 cultivated in the presence of oxygen”. The article by Monnet et al. discloses the effects of trisodium citrate addition on growth and formation of diacetyl and acetoin by Lactococcus Lactis ssp. Lactis CNRZ 483 in a whey based medium.
The article “Characterisation of a malty-compound producing Lactococcus Lactis subsp. Lactis biovar. diacetylactis C1 strain isolated from naturally fermented milk” by Mutukumira et al. (2009) Milchwissenschaft 64(1) pp. 26-29, relates to a strain that produced acceptable fermented milk to a sensory panel despite the presence of a slight malty flavour.
The article “Diacetyl production by different strains of Lactococcus lactis subsp. Lactis biovar. diacetylactis and Leuconostoc spp.” by Hugenholtz and Starrenburg (1992) Appl. Microbiol. Biotechnol 38, pp. 17-22, relates to the comparison of several strains for product formation from citrate in milk cultures.
However, due to a number of the lactic acid bacteria strains and their interactions with individuals, a selection of certain lactic acid bacteria strains to produce certain flavours and aromas in the fermented milk products is not predictable.
Fermented milk products have a wide variety of flavours and aromas depending upon the milk source and the lactic acid bacteria strains used to ferment the milk source.
There is a need to provide methods and lactic acid bacteria strains that are responsible for specific flavours and aromas in the fermented milk products.
Furthermore, artificial additives are negatively perceived by the consumer. There a need to provide flavour and aromas in a natural way that avoids artificial additives.
There is also a need to provide flavour and aromas which can be used in a wide range of foods.
There is thus a need to overcome the aforementioned problems in the art.